Pruning KiwiTed Swensen
Kiwi vines climb by wrapping around like pole beans or wisteria. So they need a support structure or host plant. My kiwi is using the deck supports and a flowering cherry tree for support. Mature female, Actinidia deliciosa, (the kiwi in stores) can produce up to 300 pounds of fruit each year. They can grow as much as 15-20 feet of vine from a single bud in a year. Therefore they require attention, training, and year-round pruning to keep them from growing over your home or in my case the deck. If the growth rate of A. Deliciosa is to much for you, you might select the hardy kiwi, A arguta. Mine only grows a few feet each year.
As in most fruiting plants, it is necessary to keep kiwis well pruned, and trained. I treat my kiwi much the same as I do grapes. Winter pruning should take place the last week in January or the first week of February. Kiwis form fruit on one year old wood just like grapes. Because kiwis grow so rapidly, Summer maintenance pruning after flowering is necessary.
Lets assume you construct a trellis. The book Kiwifruit Culture has many ideas for kiwi trellising. Which ever trellis style you choose, it should be tall enough to pick and prune from a standing position. You are going to do a lot of pruning, and hopefully a lot of picking.
Training and Pruning a Young Kiwi
End of First Season:
Develop a permanent trunk. If your vines don't grow tall enough the first year, cute them back to 3 or 4 viable buds and try again.
End of Second Season:
Develop permanent main cordons. Don't allow cordons to wrap more around the center wire for support. Tie them every 20-24 inches (50-60 cm). If they coil around the wire, they may constrict themselves in the coming years.
End of Third Season:
Develop well spaced fruiting laterals. Laterals should occur on the opposite sides of the cordon, at 10-16 inch (25-20 cm) intervals, any closer and you will have a tangled mass of vines. Laterals are kept for 2-3 years, then pruned away to make room for new ones.
End of Fourth Season:
The Basic plant structure is complete. Remove older parts of fruiting laterals. Fruiting arms can be renewed annually of left two or more years.
End of Fifth Season:
Maintenance Pruning. From this point on, prune out the old laterals as the reach the end of their useful life span. New laterals should be allowed to generate from the cordon at the base of the old laterals.
Ideal fruiting shoots are one year old, have short internodes (distance between two leaves), well developed buds, and exposed to sunlight.
Winter Pruning Established Kiwi
Your aim is to leave the optimum amount evenly distributed and well spaced 1 year-old wood on the vine. Fruiting arms should originate new the central wire with 10-14 inches (25-35cm) between each arm. Each vine must be restricted to its allocated space, otherwise it will twist around its neighbors and you will have the proverbial jungle.
If you are using the "T-bar" system, prune the hanging laterals at knee height. Then tie them up.
Summer Pruning Established Kiwi (Hayward variety)
Summer Pruning is essential to maintain a semblance of order, spacing, and light access to the fruiting wood. You will have to prune several times in a growing season. Start in April or May, when unfruited shoots, not required next season, can be removed. Erect water shoots can be cut back to a short stub with two or more buds. This will retain a growing point for more replacement fruiting arms or where spur growth can originate. Any shoots starting to curl and tangle should be shortened.
During June and July, rapid growth will occur and pruning is critical to maintain order. Shoots to be retained for next season are selected and allowed to remain and excesssive growth on a lateral beyond the fruit can be shortened to a manageable length. The "manageable" length is determined by competition for space from surrounding shoots. Remove tangles and again restrict the vine to its allocated space.
By August, growth has slowed in the Hayward cultivar (grocery store fuzzy kiwi) but may still require some pruning to prevent tangles and maintain sunlight to fruiting wood.
Pruning Male Vines
The major pruning in males takes place right after flowering. Head the flowering arms back to new growth, originating close to the leader. In July, the flowering arms should be cut to 20-24 inches (50-60 cm). If growth continues, in August or September, head to 29-20 inches (75-80 cm). Final pruning occurs in the winter.
References and Sources
- One Green World Nursery
- Kiwifruit Culture, Sale, P.R. 1985
- Kiwi Enthusiasts Journal vol. 6
- Raintree Nursery